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Vet Microbio > Pathogenicity and Infection > Flashcards

Pathogenicity and Infection Flashcards

1
Q

host

A

larger organism tat supports the survival and growth of a pathogenic microorganism

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2
Q

infection

A

a microbe growing and multiplying on or within a host
may or may not result in overt disease

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3
Q

infectious disease

A

any change from a state of health
part or al of the host is incapable of carrying on normal functions due to presence of a pathogen or its products

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4
Q

pathogen

A

any organism that causes disease

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5
Q

primary pathogen

A

causes disease by direct interaction with the healthy host

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6
Q

opportunistic pathogen

A

may be a part of normal microbiota and causes disease when the host is immunocompromised

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7
Q

pathogenicity

A

ability of a pathogen to cause disease

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8
Q

virulence

A

degree of harm inflicted on its host

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9
Q

extracellular pathogens

A

remain in tissues and fluids but never enters host cells during disease

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10
Q

intracellular pathogens

A

grow and multiply within host cells
two types

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11
Q

facultative intracellular pathogens

A

reside within the cells of the host or in the environment but can also be grown in pure culture without host cell support

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12
Q

obligate intracellular pathogens

A

only grow inside of host celss

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13
Q

incubation period

A

time between pathogen entry and development of signs and symptoms

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14
Q

prodromal stage

A

mild, non-specific signs and symptoms

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15
Q

illness period

A

disease is more severe and displays signs and symptoms

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16
Q

convalescence

A

recovery stage

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17
Q

signs

A

objective changes that can be directly observed and measured
fever, rash

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18
Q

symptoms

A

subjective changes, often used in broader score of clinical signs
pain, loss of appetite

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19
Q

disease syndrome

A

set of characteristic signs and symptoms for a disease

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20
Q

what does the host provide a pathogen?

A

protection, nutrients, and energy

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21
Q

what are three factors affecting the success of transmission?

A

virulence of invading organisms
number of invading organisms
presence of adhesion and invasion factors

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22
Q

when does disease ensue?

A

when organism produces molecules that directly damage the host cells to stimulates host immune cells to destroy infected tissue

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23
Q

animate sources of pathogens

A

humans or animals

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24
Q

inanimate sources of pathogens

A

water, food

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25
Q

reservoir

A

natural environmental location in which the pathogen normally resides

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26
Q

vector

A

organism that spreads disease from one host to another

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27
Q

what are some examples of vectors?

A

mosquitoes, ticks, fleas, mites, or biting flies

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28
Q

what are the five main routes of disease transmission?

A

airborne, contact, vehicle, vector-borne, vertical transmission

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29
Q

what increases efficiency of transmission?

A

extensive multiplication

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30
Q

tropism

A

pathogen must make contact with appropriate host tissue determined by specific cell surface receptors

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31
Q

what are the three types of airborne transmission?

A

droplets (direct)
droplet nuclei (indirect)
aerosols (indirect)

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32
Q

droplets

A

up to 2 mm in diameter
produced when liquids are placed under force (saliva, mucus, etc)
can travel <1m

33
Q

droplet nuclei

A

1-5 um in diameter
result from evaporation of the larger droplets
may remain airborne for hours or days and travel long distances

34
Q

dust particles

A

aerosolized, smaller than 1 um can be dispersed even further
microorganisms adhere to dust particles
can survive long periods outside host and can lead to hospital-acquired infections

35
Q

contact transmission

A

host touching source or reservoir of the pathogen

36
Q

what are the two types of contact transmission?

A

direct and indirect

37
Q

direct contact

A

person to person
physical interaction required
touching and sexual contact

38
Q

indirect contact

A

involves an inanimate object (fomite) that transfers infectious agent between hosts

39
Q

vehicles

A

materials that indirectly transmit pathogens
ex: surgical instruments, drinking vessels, food, water, biological materials such as fluids and tissues, and air
a single source containing pathogens can contaminate a common vehicle that causes multiple infections

40
Q

vector

A

living organisms that can transmit a pathogen
most are arthropods (insects, ticks, fleas) or vertebrates (dogs, cats, skunks, bats)

41
Q

why does the pathogen benefit from vector transmission?

A

allows for extensive reproduction and spread between hosts
highly virulent and cause diseases such as malaria, rabies, West Nile virus, etc
important that pathogens do not harm their vectors

42
Q

external (mechanical) transmission

A

passive carriage of pathogen on body of vector
no growth of pathogen during transmission

43
Q

internal transmission

A

carried within vector

44
Q

harborage transmission

A

pathogen does not undergo changes within vector

45
Q

biologic transmission

A

pathogen undergoes changes within vector

46
Q

vertical transmission

A

occurs when the unborn child acquires a pathogen from an infected mother
not as common as horizontal transmission
babies born with an infection disease are said to have a congenital infection

47
Q

infectious dose (ID50)

A

number of microbes required to cause disease in 50% of inoculated hosts
varies among pathogen

48
Q

lethal dose (LD50)

A

dose that kills 50% of a group of experimental hosts within a specified period
influenced by susceptibility of the host- immune system, nutrition, cleanliness, and emotional health

49
Q

adherence and invasion

A

entry and adhesion establish colonization

50
Q

portal of entry

A

skin, respiratory, gastrointestinal, urogenital systems, or conjuctiva of the eye

51
Q

colonization

A

establish a site of microbial replication on or within host

52
Q

adherence structures

A

pili, fimbriae, membrane and capsular materials, specialized adhesion molecules on microbes cell surface

53
Q

infectivity

A

ability to create a discrete point of infection

54
Q

invasiveness

A

ability to spread to adjacent structures

55
Q

active penetration

A

occurs through production of lytic substances that alter host tissue
attack the extracellular matrix and basement membranes of integuments and intestinal linings
degrade carbohydrate-protein complexes between cells
disrupt the host-cell surface

56
Q

passive penetration

A

not related to the pathogen itself (skin lesions, insect bites, wounds)

57
Q

bacteremia

A

presence of viable bacteria in the blood

58
Q

septicemia

A

bacterial or fungal toxins in the blodd

59
Q

why is clostridium retain considered noninvasive?

A

it does not spread fro one tissue to the other, but toxins become blood borne

60
Q

why are bacillus anthraces and plague invasive?

A

they produce toxins that spread from one tissue to another

61
Q

formation of actin tail by intracellular bacterial pathogens (listeria, shigella, etc.)

A

bacteria use cell surface proteins to polymerize host actin
actin tail propels bacteria to the hosts surface where it forms a protrusion
protrusion is engulfed by adjacent cell and evades the immune response

62
Q

list five ways that successful pathogens elude initial Jost responses and the adaptive immune system?

A
  1. survive and replicate inside host cells
  2. make capsules to avoid phagocytosis
  3. produce enzymes that inactivate innate resistance mechanisms
  4. mutate cell surface proteins
  5. squeeze between host cells
63
Q

what is phage variation?

A

switch among different genes that encode similar proteins after pili protein sequence and expressi

64
Q

how do bacteria suppress host immune response?

A

infect cells of the immune system and diminish function while ensuring their own survival
some bacteria produce a slippery mucoid capsule that prevents phagocytosis by host immune cells
eliminate O-antigen on LPS to diminish recognition and clearance

65
Q

biofilm benefits

A

biofilm bacteria are protected from nutrient deprivation, predators, environmental shifts, antimicrobial agents, and host immune cells
some pathogenic bacteria within biofilms exchange plasmids, nutrients, and quorum-sensing molecules altering their behavior
makes the biofilm community less sensitive to antibiotics and host defense mechanisms

66
Q

pathogenicity islands

A

large segments of bacterial chromosomal and plasmid DNA found to encode virulence factors
increase bacterial virulence
absent in nonpathogenic members of same genus or species
genes can be spread from one bacterial cell to another

67
Q

toxin

A

substance that disrupts the normal metabolism of host cells

68
Q

toxigenicity

A

substance that disrupts the normal metabolism of host cells

69
Q

intoxications

A

disease that result from entry of a specific preformed toxin into host
do not require the presence of the actively growing pathogen, just the toxin

70
Q

exotoxins

A

soluble, heat-ladle proteins
often travel from the site of infection to other body tissues or target cells where they exert their effects
encoded by genes on plasmids or prophages within bacteria
among the most lethal substances known

71
Q

types of exotoxins

A

AB toxin

72
Q

AB toxin

A

two subunit types:
-A catalyzes the reaction that causes toxicity
-B binds to host cell receptor
specific site exotoxins
membrane destabilizing
superantigens

73
Q

superantigens

A

stimulate about 30% of host T cells of the immune system
causes T cells to overexposes genes that encode cytokine and release pro-inflammatory molecules
results in failure of multiple host organs allowing time for the microbe to disseminate

74
Q

endotoxin-LPS

A

gram negative cell wall is toxic to mammals
called endotoxin because it is bound to the bacterium and released when the microorganisms lyses
toxic component is the lipid portion lipid A

75
Q

endotoxin general features

A

heat stable
toxic in nanogram amounts
generally similar despite source
cause general system effects
-fever, shock, damage to lining of blood vessels, weakness, diarrhea, inflammation, intestinal hemorrhage, and fibrinolysis

76
Q

mycotoxins

A

toxins produced by fungi

77
Q

aflatoxins

A

food crop contaminant
produced by aspergillum bacterias
cause chronic and acute liver disease and liver cancer

78
Q

stachybotrys trichothecene inhibit DNA, RNA, and protein synthesis

A

induce inflammation, disrupt surfactant phospholipids in the lungs, and may lead to pathological changes in tissues

79
Q

ergots

A

produce hallucinogen lysergic acid (LSD)

Vet Microbio (12 decks)

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